Control of the Shell Thickness of TiO₂@SiO₂ Particles and Its Surface Functionalization

Experimental

Preparation of TiO2 Particles.29 Two solutions were prepared: 0.45 wt ％of titanium butoxide in ethylene glycol and 2.03 mM of surfactant (Tween 20) in acetone containing a small amount of water. The titanium butoxide solution was mixed with the Tween 20 solution. After stirring for 1 day at room temperature, solution was centrifuged for 10 min at 3000 rpm.

Preparation of TiO2@SiO2 Particles.29 TiO2 particles (0.082 g) were dried for 2 h at 323 K. The particles were dispersed in 100 mL of ethanol under the sonication and then 5 mL of aqueous ammonia solution was added to the dispersion. Tetraethyl orthosilicate (TEOS) (2 mL) was added to the dispersion. After stirring for 10-40 min at room temperature, the solvent was removed by centrifugation at 3000 rpm for 5 min. The resulting powder was calcinated at 873-1273 K for 15 minutes.

Preparation of Acryl Functionalized TiO2@SiO2 Particles. TiO2@SiO2 particles were dispersed in a solution of 1.5 mL of ethanol, 1.7 mL of water and 1.25 mL of aqueous ammonia solution under sonication for 10 min. 3-(Trimethoxysilyl)- propyl acrylate (0.1 mL) was added to the solution. The solution was stirred for 1 day and the particles were collected by centrifugation at 3000 rpm for 10 min. The resulting particles were washed with ethanol and dried in vacuum.